WASHINGTON (AP) — A New York marketing executive received more than $600,000 in illicit funds to do unsolicited campaign work for a 2008 presidential candidate, federal prosecutors in Washington said Wednesday.

Troy White pleaded guilty to a misdemeanor for failing to file tax returns reflecting the amount his company, Wytehouse Marketing Inc., was paid. But court documents outlined an elaborate scheme in which White allegedly worked with District of Columbia businessman Jeffrey Thompson to help a presidential candidate during several Democratic primaries in the winter and spring of 2008.

While the candidate was not identified in court documents, an attorney for Hillary Rodham Clinton’s 2008 presidential bid confirmed that the case involved her campaign.

Thompson and his network of donors were major contributors to Clinton’s presidential bid, and White’s website highlights the work his company did for Hillary Clinton and the Bill Clinton Foundation.

White had discussions about working for the campaign but was turned down, the documents show.

“Hillary Clinton for President has cooperated fully in the matter involving Troy White,” Lyn Utrecht, a lawyer for her 2008 campaign, said in an email Wednesday. “As the court document filed in this matter clearly states, the Committee turned down Mr. White’s services. The Committee will not have any further comment in an ongoing investigation.”

According to prosecutors, a campaign official then introduced White to a businessman matching Thompson’s description, who then funneled $608,750 to Wytehouse through Belle International Inc., a company owned by Eugenia “Jeanne” Clarke Harris, a close Thompson associate.

Although he is not identified in the court documents in the White case, two people familiar with the investigation said the unnamed executive is Thompson. The people spoke on condition of anonymity because they were not authorized to discuss the person’s identity.

The money paid for “street teams” that worked to increase the candidate’s visibility in urban areas ahead of several primaries, starting with the Texas primary and caucuses in March 2008. Clinton narrowly defeated Barack Obama in the Texas primary, and Obama won the caucuses.

Texas was considered a critical state for Clinton during her lengthy battle with Obama for the Democratic nomination.

According to the court documents, the campaign official “provided White with confidential internal information … regarding the itinerary and schedule for a high-profile individual who would be campaigning in Texas.” White sent workers to those events to show support and distribute campaign materials, the documents show.

Thompson is also the subject of a grand jury investigation, according to court documents. His lawyer has repeatedly declined to comment.

Three former Thompson associates, including Harris, have admitted in court to making more than $300,000 in straw contributions on his behalf to federal and District of Columbia candidates.

According to a database of Thompson-affiliated donors compiled by The Associated Press, Thompson and more than 50 of his associates — including employees, relatives, business associates and friends — gave more than $100,000 to Clinton’s 2008 presidential campaign.

The scheme to fund White’s campaign activities is similar to what Thompson is alleged to have used to help Vincent Gray get elected as District of Columbia mayor in 2010. Harris pleaded guilty to funneling $653,000 through her companies, including Belle International, into Gray’s campaign. Prosecutors described the effort as a “shadow campaign” that tainted Gray’s Democratic primary victory over then-mayor Adrian Fenty.

White and his attorney, Ross Nabatoff, declined to comment after the hearing Wednesday afternoon. White, 48, faces a maximum of one year in prison for the misdemeanor conviction but is likely to receive less time under federal guidelines. He agreed to cooperate in the ongoing investigation, and his sentence could be reduced for substantial cooperation.